This invention relates to a novel liquid crystal compound and a liquid crystal composition containing the compound.
Liquid crystal substances and compositions thereof have been used for various display devices, utilizing the dielectric anisotropy (hereinafter abbreviated to .DELTA..epsilon.) and the optical anisotropy (hereinafter abbreviated to .DELTA.n) in the liquid crystal phases thereof.
Liquid crystal display modes include various ones such as electric ally controlled birefringence type (ECB type), twisted nematic type (TN type), super twisted birefringence type (SBE type), dynamic scattering type (DS type), guest-host type, etc., which correspond to various electro-optical effects applied.
Liquid crystal materials used for display devices should provide together various specific features such as a broad mesomorphic range, a low viscosity, a large positive .DELTA..epsilon. value or a negative .DELTA..epsilon. value, no notable change in various specific features (particularly, threshould voltage) over a broad liquid crystal phase temperature range, etc., depending on the display modes thereof or on various specific features required for the display elements thereof.
At present, however, there is no single compound which is practically usable, in the aspects of liquid crystal phase temperature range, driving voltage and response performance. Thus, for practical use, mixtures of several kinds of liquid crystal compounds or mixtures of several kinds of liquid crystal compounds with compounds having latent liquid crystal properties or non-liquid crystal compounds have been used.